Art of well drilling



May 29, 1951 c. D. MILLlsoN ART 0F WELL DRILLING 3 Sheets-Sheet l Filed May 20, 1946 TAL May 29, 1951 c. D. MILLIsoN ART 0F WELL DRILLING 3 Sheets-Sheet 2 Filed May 2o, 194e '56 ,I Yv @MARK DMILLlscm 2&3 M *LM cz. oc/f WUR/f MECH/:MSM

May 29, 1951 c. D. MILLISON 2,555,275

ART oF WELL DRILLING Filed May 20, 1946 3 Sheets-Sheet 5 MINUTES gin/UMKC@ CLPQRM D MIL/LIS ON Patented May 29, 1951 Clark D. Millison, Tulsa, Okla., assigner jtozCox'e Recorder, Inc., Tulsa, Okla., a corporation of Oklahoma Application May 2o, 1946, serial No. 671,023

s claims. (c1. Vc55- 1.4 i

1 The present invention relates generally `to the art -of well drilling.

More particularly-it relates to an improved oil Well surveying instrument adapted to be employed in conjunction with rotary core .drilling equipment to determine the character and location -of the various earth strata through which the -well is drilled.

In the normal operation of a rotary drill rig for the drilling of oil and gas wells, the cutting tool or rock bit is supported at Athe lower end of astring'of drill pipe .known as the drill string,

which is rotated bjr-machinery at thesurface acljacent the top of the well. A-column of Weighted fluid known as drilling mud is continuously forced under pressure down through the drill string and out at the bottom adjacent the cutting tool where it serves to lubricate the latter and control the well pressure, as well as to wash the cuttings and bits of formation material -envcountered through `the Iouter casing which surrounds the drill string and up to the surface where it-is discharged into a slush pit; The personnel in ch-argeof operations carefully observes the drilling mud as it returns .to the surface and thereby estimates the nature of the formation in which the-cutting tool is operating. This method of determining the character of the formation is necessarily inexact and accordingly it is common practice to restort to coring operations periodically, particularly as-the drilling approaches a depth where producing formations rinay be anticipated.

The core drilling operation is accomplished by substituting an annular-shaped core bit for the usual cutting 4tool and yproviding a hollow -cylindrical chamber called a core barrel open to the center of this core bit for receiving a centrally projecting plug of formation material which is left relatively intact at the bottom of the well as the core bit progresses downwardly. As soon as the core drilling has proceeded the desired distance, suitable steps are taken, such as speeding up the drilling, to break off the projecting core which is retained by a suitably designed core catcher Within thecore barrel and may be brought to the surface and removed from vthe well for observation to 'determine the precise nature of the formation which has been drilled through. However, it happens in many cases, Iand particularly where potentially productive formations are being cored, that a substantial portion of the Vcore -sample may `escape from the core vbarrel or be otherwise lost so Athata complete sample of each formationxencountered is not obtained.

Accordingly, the present invention has for its Yprincipal object the 4provision of ,an improved :core drilling apparatus wherein means are pro- .vided for determining 4theamount obtained and ;time.rate of yrecovery and loss of the-core sample.

Another object of theinventon is the provision of a novel instrument for use in conjunction with core drillingapparatus includinga recording Vdevice whichis driven ata timed rate .and ,which is alsoresponsiveto movement of thecore sample within the core barrel for Yautomatically recording the directionand timerate of such movement.

A .further object of the invention resides :in the provision. of a .novel instrument of the .type referred to including a spring tensionedwireline and reduction gearing .mounted therewithin .for recording the directionof movement of the core sample within thecore barrel .ata reduced `rate .as the .instrument .itself moves within thecore barrelunder the influence Aof gravitational f orce.

AAn additional `object ofthe invention is toprovide .an instrument for .recording the direction and time rate of .movement of acore sample ,of formation material within .acorefbarrel wherein 1the instrument is practically self-contained and is sealed in .such manner vas to prevent the` entrance of drilling .-uid or foreign particles.

A .still further object of .the invention resides .infa novel method of surveyingan oil wellwhere.- by Vthe .amount .and `time -rate of recovery and loss :of the core sample are accurately measured, recorded for ,each increment .drilled .and .correlated with the V.core sample obtained.

Other and ffurther y.objects .and .advantages .of the present invention as well as a morecomplete `understanding thereof will become more readily apparent from aconsideration of the following Vdetailed .specification taken fin `conjunction with the accompanying drawings vand illustrating a preferred ,embodimentthereoi wherein:

Fig. 1 is a longitudinal section through the bottom of a bore holehaving a vcore drilling apparatus in accordance with thepresent invention in operative position therein;

Fig. 2 is a partially sectioned front elevational viewofthe novel instrument constituting a principal part of the .present invention;

Fig. 3 is a partially `sectioned side view of the instrument shown in Fig. 2; and

Fig. 4 is atypical record chart obtained by use of the instrument illustrated in Figs. 1 to 3.

Referring now in Vmore detail to the various lfigures of drawing and in Vparticular to Fig. I1, lthere is illustrated the bottom portion of a boring wherein the drill'hole is designated generally `by ly freely upon the top of the core sample 21. .recording instrument 29, in accordance with the .drilling progresses.

-pressed plungers 31.

I8 having an outside diameter appreciably` smaller than the internal diameter of the sub I is mounted in suitable bearings I9 within the `outer core barrel I6 and is provided with a section of tubing constituting av fluid connection from the inside of the inner core'barrel to the well ID through a fitting 2|, the latter being provided with an aperture 22 and pipe 22a extending through a matching aperture in the side wall of the collar I4. A suitable packing 23 is provided at the juncture of the tube 20 with the inner core vbarrel I8, 'and a one-way ball check valve 24 is mounted in a plug 25 secured in the top of the inner core barrel I8 to permit the escape of fluid from the interior of the inner core barrel while preventing the entrance of drilling .fluid or extraneous material.

A core catcher 26 which may be of any suitable construction is mounted in the lower por- .tion of the inner core barrel I8 and serves to retain the core sample 21 therein upon the completion of a core drilling operation. A typical plug 28 is provided in the lower portion of the inner core barrel I8 to prevent the entrance of drilling fluid or other foreign material into the bottom thereof until the core drilling operation is started at which time the plug 28 rides relative- The present invention, is generally cylindrical in shape and rests upon the top of the plug 28 in such manner that it may be freely moved longitudinally within the inner core barrel I8 by the plug 28 as the latter is forced inwardly relative to Ithe inner core barrel by the core sample 21 as The instrument 29 and plug V-28 are also free to move downwardly relative to the inner core barrel I8 under the influence of gravity should any relative motion in a. downward direction of the core 'sample 21 occur. A wireline .30 .is secured to a swivel' 3I attached to an aper- Ytured cap 32 which in turn is mounted on the bottom of the plug 25. The Wire line 3U extends downwardly through a suitable packing gland 33 vin the top of the instrument 29'for a purpose to be described.

Referring now particularly to Figs. 2 and 3, the instrument 29 is seen to comprise generally an outer cylinder 34 and an Vinner cylinder 35.

vThe bottom end of the outer cylinder 34 is closed by a relatively flat cylindrical housing 36, suitably mounted therein as by means of spring- (See same element 49 for details.) The housing 36 contains a Clockwork Mechanism, partially shown in Fig. 2, secured indriving relationship as by means of screws 36a to the bottom plate 38 of the inner cylinder 35 for rotating the cylinder 35 relative to the cylinder 34 at a timed rate'. The top end of thel outer cylinder 34 is substantially closed by a cap piece '39' which is releasablyV secured therein by means of a plurality of spring-pressed plungers 48, the reduced outer end portions of which fit into apertures 4I formed in the side wall of the outer cylinder 34. As will be particularly noted in Fig. 3, -the packing gland v33 is in Ysealing engagement with the wire line 39 to prevent the entrance of fluid or foreign particles to the interior of the instrument 29.

Depending from the upper cap piece 39 are a plurality of journal frames 42, 43 and 44, which project downwardly within the inner cylinder 35 in spaced relation to the inner and bottom Vwalls thereof. These journal frames are formed to provide aligned journal bearings for a plurality of parallel shafts 45 to 51, inclusive, which are freely rotatable therein. A pulley 58 secured to theshaft 46 is connected in driving relation, by means of a train of reduction gears 59 to 10, inclusive, to a sprocket 10a secured to the shaft 53. Power for operating the sprocket 18a and its associated gear train is supplied by means of the wire line 39 which extends through the packing gland 33 in the top of the outer cylinder,

around the pulley 58 in driving relation thereto, over an idler pulley 1I, and thence downwardly into the inner cylinder 35 where it is wound upon a drum 12 secured to the shaft 56. The drum 12 is tensioned to constantly draw the wire line 30 into the cylinder 39 by means of a spring motor 13 mounted in the lower portion of the journal frame 42 and connected in driving relation to the drum 12 by means of a train of gears 14 to 18, inclusive. The sprocket 19a is in turn connected in driving relation to an endless link chain 19 which is freely movable over a pair of idler sprockets and 8|, and carries a recording element in the form of a stylus 82 adapted to move relatively across the surface of a chart 83 in contact with the latter. The chart 63 is removably attached to the inner wall of the inner cylinder 35 and cooperates with the stylus 82 to produce a graphic record of relative movement between the stylus 82 and the inner cylinder 35.

The operation of the device is as follows: Referring again to Fig. l, the core drilling apparatus is shown in the position which it assumes at the bottom of the well a short time after the core -drilling operation has begun. The cutting tool or core bit I1 has progressed downwardly a short distance d cutting into the formation and producing an annular hole 84 as the drill stem I2 is rotated. During this core'drilling operation the drilling fluid has been forced downwardly through the drill stem, into the sub I5, through the annular space between the sub I5 and the inner core barrel I8, through an annular passage 85 formed in the body of the tool and out around the core bit I1, lubricating the latter and washing the cuttings to the surface at the top of the well through the outer portion of the drill vhole I0. As the core drilling proceeds, the inner core barrel I8 is forced downwardly around the inner plug 21 of formation material. The plug 28 which rests upon the upper surface of the core sample 21 is thus forced upwardly relative to the inner core barrel IB carrying with it the instrument 29 which rests upon the top of the plug 28 by its own weight. Actually, of course, the inner core barrel I8 is forced downwardly about the instrument 29, the plug 28, and the core sample 21, but this is immaterial since it is the relative movement between the instrument 29 and the inner core barrel I8 which'is of primary importance. At the conclusion ofthe coredrillying operation the core sample 21 is broken off at the bottom in any well known manner and the entire apparatus brought to the surface, the core sample being retained in the inner core barrel I 8 rby ymeans -ofA the core catcher 26.V The core barrel I8 in any common manner and may then be analyzed to determinethe` nature of the formations` at the bottom of the welll.

As the inner core barrel I8 moves downwardly about theI instrument 29, the wire line 30 which moves with the core barrel is drawn into the instrument by the action of the spring-tensioned drum 12. Since the Ywire line 38 is connected in driving relation tothe pulley 58', this movement of the wire line 30 into the instrument serves to rotate the pulley B and, through its associated gear train 59 to 10, inclusive, the drive sprocket 10a, and link chain 19'-, imparts a vertical movement to the stylus 832.. This movement is proportional to the relative movement between the in'- strument 29- and the inner core barrel I8 but of much smaller magnitude due to the action of the reduction gear train 59 to 19, inclusi-ve. At. the same time, and throughout the core drillingoperation, the inner cylinder 35 carrying the record' chart 83 is being rotated: at a timed rate by means of the clockwork mechanism in housing 36. Thus the line which is traced by the stylus 82 upon the record chart 83 is a resultant of' the rotational movement of the chart 83- relative to the stylus 82 and the longitudinal, translational movement of the stylus produced by the relative movement of instrument 29 and the inner core barrel I8 through the action of the wire line 39, the spring-tensioned drum l2, and the link chain 19 and its reduction gear train and pulley system 58 to` 10a.

A typical curve produced during a core drilling operation as just described is illustrated in the chart of Fig. 4. This chart has ordinates dening the relativedistancemoved feet between the instrument 29 and thel inner core barrel I8 and has abscissae measuring in minutes the tota-l time elapsed during the particular core drilling operation. That portion ofthe curve designated by the reference numeral 86- produced as core drilling progresses normally with a formation sample moving relatively into the core barrelk I-8 as the hole is deepened. Those portions of the curve indicated by reference numeral 8'I are produced as drilling is continued but no core sam- (i cordingly serves as a further indication of the nature of the formation material through which the drill' was progressing. The chart 83 may eventually be used in completing the well survey in accordance with any of several recognized procedures.

While there have beenA disclosed in detail a preferred form of apparatus and a preferred method forpracticing this invention, it is to be understood that numerous variations can be made therein without departing from the spirit thereof and the scope of the appended claims.

Having thus described my invention, what I claim as novel and desire to secure by Letters Patent of the United States is:

l. Core drilling apparatus comprising a core barrel adapted to receive a core sample of formation material therein, and an instrument; disposed within the core barrel for recording the direction and time rate of movement of the core sample within saidl core barrel, said instrument comprising an outer, hollour cylinder responsive to such movement, a clock mechanism in the bottomof said outer cylinder, an inner hollow cylind'er concentrically mounted within said outer cylinder and having a record chart secured to its inner walLVsaid inner cylinder being connected ple is obtained, or by a temporary discontinuance v of the core drilling operation (the time period for which would be observed or recorded at the surface), in either of which events no relative movement between the instrument 29 and the inner core barrel I8 will take place. That portion of the curve designated' by reference numeral 88 illustrates a relative movement between the instrument 29 and the core barrel I8 in an opposite sense, that is, one ih which the sample of formation material has moved relatively out of the core barrel and is lost. Theportion 89 of the curve indicates a uniform rotational movement of the chart relative to the stylus during which no relative motion between the instrument 29 and the inner core barrel I8 takes place and is normally produced after the core drilling operation has ceased and while the core barrel is being lifted out of the well. When considered with the known times of core drilling and removal operations, the resultant curve illustrated in Fig. 4 serves to give a complete picture of the amount of core sample recovered and lost and. in conjunction with the known total depth drilled, also indicates the precise location of the core recovered and lost. It will be understood that the slope of the curve at any point corresponds `to the rate at which the core drilling operation was proceeding at that particular time and acto said clock mechanism for rotation thereby relative to said outer cylinder, a journal frame depending from the top of said outer cylinder within but spaced from said inner cylinder, rst and second gear trains journalecl in said frame, said rst gear train including a pulley and a link chain having a stylus thereon engageabl'e with said chart, and said second gear train including a spring motor and a drum at oppositev ends thereof, and a wire line tensioned from the top of said core barrel extending around said pulley to said drum, whereby said stylus is moved vertically along said chart in response to vertical movement of said outer cylinder and said chart is rotated by said clock mechanism relative to said stylus.

2f.. In a core drilling apparatus having ay core .L barrel adapted to receive a sample of formation material therein, an instrument disposed within the core barrel for recording the direction and time rate of movement of the sample within the core barrel comprising a rst generally tubular member having its ends substantially closed, a second generally tubular member mounted within said first member, means for relatively rotating said members, a chart attached to said second member, a frame secured to said first member and lying within said second member, a stylus operatively associated with said chart, means including a pulley and reduction gearing mounted in said frame for moving said stylus over said chart, a exible line secured at one end to the core barrel and passing around said pulley in driving relation thereto, and a spring-tensioned drum mounted in said frame and having the other end of said line wound thereon, said drum being arranged constantly to urge said line into said members whereby said stylus is moved over said chart in response to relative movement between said instrument and the core barrel.

3. In a core drilling apparatus having a core barrel adapted to receive a sample of formation material therein, an instrument disposed in the core barrel and comprising a i'lrst member movable Within the core barrel in response to movement of the sample therein, a second member movable at a timed rate relative to said rst member, a-record chart attached to said secondl member, a recording stylus operatively associated with said first member, mechanism for moving said stylus over the surface of said chart in response to relative movement of sample and core barrel to record the direction and amount of movement of the sample within the core barrel, and drive means for producing uniform relative rotation between said rst and second members whereby the stylus will also record the time rate of movement of the sample within the core barrel.

4. The method of surveying an oil well which comprises the steps of drilling a core sample of the formation material at the bottom of the well, incrementally and continuously measuring the amount and time rate of recovery and loss for the core sample obtained, removing the core sample from the well, and determining by correlation of the measurements of amount and time rate of recovery and loss of core sample with an analysis of the core sample removed the characteristics of the formation material in the various drilled strata.

5. In combination with a core drilling apparatus having a core barrel adapted to receive a sample of formation material therein, a selfcontained, sealed and generally cylindrical instrument disposed within the core barrel and comprising rst means responsive to movement of the sample within the core barrel, second means movable relative to said rst means, driving means for moving said second means at a timed rate relative to said rst means, and indicator means operatively associated with both said first and said second means and constructed and arranged to record the direction and time rate of movement of the sample within the core barrel.

6. The combination of claim including a plug movable upwardly within the core barrel on top of the sample.

'7. Drilling apparatus comprising a tubular cutting tool, a core barrel mounted in said tool and adapted to receive a core sample of formation material therein, an elongated generally cylindrical recording instrument disposed in the core barrel and including enclosed recording means continuously responsive to movement of formation material within said core barrel, and en-l closed record receiving means continuously movable at a time rate relative to said recordingl means for indicating the direction and time rate of such formation material movement.

8. A core drilling recording instrument adapted to be disposed in a formation sample receiving core barrel for recording the vdirection and time rate of movement of the sample within the core barrel, said instrument comprising a first tubular member having its ends substantially closed and sealed, a second tubular member mounted within said' rst member, means for relatively rotating said members, a chart attached to the inside ofv said second member, a frame secured to said rst member and lyingwithin said second member, a stylus operatively associated with said chart, means including a pulley and reduction gearing mounted in said frame for moving said stylus over said chart, a flexible line extending from one end of rst tubular member and having an inward portion passing around said pulley in driving relation, and a spring-tensioned drum mounted in said frame and having the other end of said line wound thereon, said drum being arranged constantly to urge said line into said members whereby said stylus is moved over said chart in response to relative movement between said line and said tubular members.

CLARK D. MILLISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 455,037 Gardner June 30, 1891 1,283,542 Murphy et al Nov. 5, 1918 2,096,995 Mizell Oct. 26, 1927- 

